VII. SUMMARY AND CONCLUSIONS 



During the period from 1964 to 1975, 2,952 repetitive beach profiles 

 were recorded at 241 stations between Wrightsville Beach and Fort 

 Fisher Beach. The total length of Wrightsville and Carolina Beaches 

 represented only 32 percent of the total length of the study area, but 

 nearly 70 percent of all beach profile stations and 89 percent of the 

 total number of recorded profiles were located along these two beaches. 

 Of the nearly 3,000 profiles, only 4 percent extended beyond the MLW 

 position to approximatley the -10 meter contour. As a consequence, 

 volumetric changes representative of actual changes occurring between 

 successive surveys could not be calculated by simply measuring the 

 change in area under the measured profile curves because significant 

 changes occur below the low water line. 



The positions of the MHW, MSL, MLW, -1.83 meters (-6 feet), 

 -3.66 meters (-12 feet), and -5.49 meters (-18 feet) contours were 

 plotted relative to a fixed base line, for all profiles. The excursion 

 distance of each contour between successive profiles is indicative of 

 volumetric change, the magnitude of which is found by applying a 

 volumetric equivalent factor, calculated from changes in area under some 

 profiles which repetitively extended out into deeper water, to the mean 

 excursion distance value. Due to the poor spatial and temporal 

 distribution of profiles along Masonboro , Kure, and Fort Fisher Beaches, 

 only profiles from Wrightsville and Carolina Beaches were used in the 

 analysis of beach response and volumetric changes associated with storms 

 and manmade influences. The results indicate that the average seasonal 

 changes along Wrightsville and Carolina Beaches, measured 24 and 

 17 meters, respectively, were significantly larger than the long-term 

 loss (erosion) rate for 1 year. In addition, the response of these 

 beaches to storm-induced erosion or beach-fill placement was, in many 

 instances, very short in duration and therefore difficult to identify in 

 many of the excursion plots which had poor temporal resolution. 



Most of the beach profile data are not a result of one coordinated 

 and well-planned study, but rather from several independent and over- 

 lapping studies. The following recommendations on the distribution of 

 beach profile surveys are based on comparison of adjacent profiles and 

 are made so that the most efficient use of manpower and money can be 

 incorporated into future beach studies. 



The spatial separation of profiles should be in the range of 0.5 to 

 1.0 kilometers, if possible, along straight or smoothly varying 

 stretches of beach. Profiles should be spaced closer in areas of abrupt 

 changes in beach planform (e.g., inlets, headlands, etc.) or in areas 

 where historic observations indicate large relative changes in beach 

 position. 



The profiles must be measured with sufficient frequency so that 

 seasonal fluctuations and longer term trends can be identified and 

 separated. To accomplish this, some stations (e.g., every fourth) must 

 be surveyed frequently, no more than 1 or 2 months apart, and the inter- 

 mediate stations should be profiled at least twice a year (surveyed at 

 the same times each year) . 



92 



